In recent years, a gas circuit breaker with enlarged capacity has been developed along with the development of a high-voltage and high-current electric power system. On the other hand, there is an increasing need for cost reduction and space saving by optimization of a breaker part structure, and it is required to ensure excellent breaking performance with further lowered operation force.
Generally, in a moving side breaker part of the gas circuit breaker including a heat puffer type circuit breaker, an insulating nozzle and a moving main contact are provided on a fixed side and a breaker part side more than a puffer cylinder side. The insulating nozzle is provided for the purpose of effectively blowing arc extinguishing gas that is compressed within a puffer cylinder to arc which occurs between a moving arc contact and a fixed arc contact.
As means for improving breaking performance, there is a method of increasing a pressure of arc extinguishing gas within the puffer cylinder by increasing a throat part of the insulating nozzle. In this method, as the circuit breaker is required to break a high-voltage and high-current, a large insulating nozzle becomes necessary.
A gas circuit breaker, in which a nozzle is divided into a first nozzle member including a nozzle throat part and a second nozzle member in an axial direction thereof, and the first nozzle member and the second nozzle member are fixed to a puffer cylinder by a moving conduction contact, is disclosed in PTL 1.